| 摘要 |
<p>PURPOSE:To obtain an electron gun with a high luminance and long life by constituting the gun by use of a convex Wehnelt and a single crystalline LaB6 cathode. CONSTITUTION:Part of the electron discharging surface of a cathode chip 2 with a protruding end consists of <100> surface of a single crystalline LaB6 cathode 4. A Wehnelt 6 having an internal cone angle not less than the vertical angle of the cathode chip 2, is placed between the cathode 4 and an anode. Owing to the above constitution, electrons discharged from <100> surface and appearing on a circular cone surface 4 of the cathode chip 2 form a crossover, which has a large current density and a small diameter. As a result, a luminance over 10 times that of a W hair-pin cathode can be obtained, and an electron gun of high stability can be obtained.</p> |
